I have a 1999 5.3 silverado. I have the MAF screen delete, CAI, The little air tornado thing in the intake, and It is straight piped for now. I have read that you lose a lot of bottom end power w/o the stock muffler and I don't know whether to put a muffler back on it or not it, sounds good but it's not too loud. I really want a lot off the line and i will probably will get a tuner before long so i don't know if should put a glasspack on it or leave it straight piped.